Screw driver



NOV. 11, 1930. E MUELLER 1,781,470

SCREW DRIVER Filed April ll, 1950 l 10 driver shaft into the shank. r Fi ure 3.

Patented Nov; 1,1-, 193e l' i s" 1,781,47ll- UNITEDfsrATEs] PATENT oFFica EMIL mummia, or cameron, naomi :snm

4scanw'nmv'nia.. .ippiioation mea' apra-11, ieso. sensi no. 44am;

My invention relates to that type of screw Fi re 3, a similar` view of the same with drivers wherein a centrall disposed gripthe river shaft advanced andthe plunger ping member inthe screw river shank ,temtip in gripping engagement withthe screw,-

porarily engages in the screw slot while the Figure 4, a tranosverse section taken on line.

5 'screw setting operation is in progress. 11e-4 of Figure 2, 'l '55 An object of my invention is to cause the Figure 5, a front end elevation of the ff plunger to grip the lateral walls of the screw driver with the parts'positioned as shown in slot automatically, with extreme tightness, Figuresl and 2, and j and by the forward thrust of the screw Figure 6, asection, taken 'on line 6-6 of f "l0 Another object is-to furnish a guide to ike reference characters indicate like :direct the shaft point in the screw slot, an parts throughout the views. f y

advantage particularly,' but not exclusively The shaft of my-screw driver as herein in use upon watch screws which are-too smal shown comprises an outer or up er solid sec' 'A 15 to be manually supported while applying the tion 10 and an inner or lower tu ular section 65 2 slot.

screw driver. 11. The former carries `the'handle v13 into A further object is to leave one hand -`of whose end extends thetape'ring outer extremthe operator free for any other desired use. ity of the section. 10 vtransverselyv `perfowhileinserting the shaft /p/oint into the screw rated at 15 to recei e a locking pin 16 travi ersiiig the handle d perforations 17 ine/a 70 Further objects are to Aprovide in a single ferrule 18 thereon. The inner, end ortion helical structure means for both rectilineally 19 of the section `10ris ofreduced diameter advancing the plunger and circularly turnt0 form a plu which isv asliding fit in a ingl the same; and' to maintain such a helical socket formed y a longitudinal bore 20 ex- ?"b structure in a permanently tensioned and tending centrally throughout the length of 75 I i highly energizedcondition. the tubular shaft section 11, and of reduce?. A still further object is to make unnecesdiameter adjacent its lower vextremity as at sary the usual independent preliminary en' 21. A locking in 23 passes through. perfoe0 up tremity 'of n ergizing of a gripping rod spring and the rorations 24 in t e section 11, and' through a v' "v9 tation of the ro during every insertion of diametrical hole' 25 in lthe plug 19. The 80 the latter into a screw. slot. L lower end of the shaft section 11 is opposite- Y Additional objects are facilityl of assem- 1y reduced to form a ilat broad thinpoint 26 1 blage, a minimum of parts, strength tand ease bifurcated as at 27 by the bore. v v o of manipulation. Y Mounted to slide circularly and longitudi-v '5 To the above ends essentially m invention nally in the bore is a plunger 28 comprising 35 consistsin such. parts and in suc 'combina- -a body or bearing portion 29 slidabl engagtions of parts as fall within the scope of the ing the inner face of the tubular s a'ft secappended claims. Y tion 11, and a reduced inner end portion 30. In the accompanying drawings which Integralfwith the outer end of the bodyp'or# 4 0 form a part of this invention tiony is a stem 31 s lidable in 'an axial opening Figure 1 is a side elevation of a screw 32 in the plug 19. The plunger port1on 30 driver embodying'my invention with the tip which occupies the bifurcation ofthe point of the plunger shown in normal position, has its inner end oppositely reduced to formA anda ortion of the driver handle being 'a flat vtip ortion 33. As will hereinafter beshowi roken away, come evi ent, in the normal position of the 95 .Figure 2, an enlarged, partially fragmenplun er, the -iiat faces of the tip 3 3 are distary, 'longitudinally' central' section of the pose similarly to those of the point 26 but ,'same, and a fagirlieiligjiarg1 side elevaiioln of a in tailcv'ance ofarid belpwfhthe 1latter. n the screw en a e on t e' exten e un er wi rawn osi ion o e p un er e eX- 'v g g y yf P 'g the tip is coincident Wththe end 100 'as plug 19 being -serted in its lhe slot is enclosedby.

nallyl disposediingers 47 and the'opposite end coils of a helical' bayonetv slot comprising'alongitudinal portion 36 `anda portion 37 extending-transver'sely from'the'upperend of the portion 36. a milledring 40 loose on the shaft and provided with a iperforation 41 in whichis frictionally fixed'theouter end of a pin 42 extending into a transverse hole 43in the plungerportion29. 'By this construction the ring and plungerare fixed relatively to each other and move in unison either longitudi-nally or transversely of the shaft in the bayonet slot. f

Eccentrically or noncentrally'fdisposed in the ad'acent ends ofthe plunger portion 29 and o the reduced portion 19 ofthe shaft section 10, are cavities 44' and 5 respectively in which are respectively-se ted longitudi- 48 formed in surrounding 'the stem 31. It is essential that the spring act not dnlytorsionally to impart rotation to theplunger but that vit furnish. propulsive rectilinear downward or inward movement thereto also,

amount of energy of both torsional movement 4and rectilinear drive be initially and permaf nentlystored up in the spring. rI "his is attained thus vin the initial assemblage-of the parts. The spring 5Q in uncompressed and nontorsional ositlon and condition has its ends inserted 1n their respective cavities, the

uninserted or but partially insocket; whereupon Ithe plug is next manually twisted and simultaneously advanced into thebore 20 until torsional and in Figures l-and 2, whereby the end of the itin'g againstthe 53, the operatorgraspsI the handle 13 and'forwardly thrusts the .driver and thereby iii- /stantly forces the tip 33 inwardly until v-it is co-terminal with d1rect ener is stored -up in the spring, whereupon t e parts are immovably fixed by the insertion of the locking pin 23 into the '.slllaft perforations 24 and the hole .25 of the p ug.

With the parts norma ly disposed, as shown vprojecting plun er tip 33 1s initially abutase of the slot 5 2 of a screw the shaft point' '26.5 'This thrust partially ,slot 52,'as show-n i p1n 42 which has reached the top of the bayonet slot portion 36, automatically, by the tor- 50, snaps' intol the `The positionfo Athe plunger Aand ofthe lock# 1n g pin"42 at this locked stag/e is shown in lgure lontemporaneously with the grip spring 50"" and that an adequate The operation of Inv device is as follows.

-in the -bore including a tip `vance'of the point,'a compressible torsional rotates the plunger' and?V brought the corners of the tip 33 into gripl ping contact with the side wallsof the screw' n 'Figure 6, whereupon thef e bayonet slot, and

ing pin slidable in ping and locking action of the plunger thel operator turns tliehandle 13 to advance the excessive advance by the pin 42 in the lower extremityof the slot. 7

It will be.. observed that thc plunger retreats vand locks automatically Without any manual manipulation of the bayonet slot pin 20, ring 40, or other auxiliary device, and that the only manipulation of the pin or ring. for auypurpose whatever, is the slight turna of the lattertransversely of the shaft only, to expose the plunger tothe propulsive action ofthe spring plunger to original projecting position.

*The operator is not required to manually,- either directly or indirectly, independently manipulate-the -grippiiig member during the insertionof the screw driver into the screw slot, therefore he haso'ne hand free for other purposes prior and while inserting'the screw.

It will be noted that the sectional charac# 10 for the-return of the position, where it remains -checked against ter of the shaft andthe means for interengagsioning the spring, and permanently maintaining the'tension, intensities the torsional, rotary, or gripping action ofthe plunger, as

well as furnishes the power necessary to forcefullypropel the plunger rectilineally.

I clalms- 1. In a screw driver of the character described, a shaft including a'broad point and provided with an axialbore bifurcating the point, and with a lateral bayonet slot, a handle upon the end of the shaft opposite the tip, an oscillatory plunger slidably mounted normally in adspring in the borel engaging and abutting the end ofthe plunger, and a locking, pin in the plunger slidable in the islet;

2 In a` screw driver. of the 'character deascribed,

a' shaft including a broad point and provided'with a central longitudinal bore exal tending through the point, and with a lateral 1 bayonet; slot, a .handle fast, to theA shaft, a

cillatory plunger slidably mounted in the bor including-a portion movable in of thepointandkprovidedwith a ti regis terable with the-point, a spring in t e borel both rojecting th plunger and in one posit1on ringing the plunger under torsional stra1n,a ringfloose' on the shaft',and a loclr the slot-j and fast in the.

plunger and ring. '4

los

12o: longitudinally movable'and' transverselyosf adyance racimo 3. In a screw driver of the character described, a handle, a shaft comprising a section provided with a centralv longitudinal bore, an intermediate ba onet slot, end wlth perforations near one en and a section fixed at one end to the handle andl including a terminal reduced portion loose in the bore protion having a vided with a transverse hole and with an eccentrically positioned cavity in its end, an

oscillatory yieldin Agripping plungerslidably mounted 'in t e bore and provided in one end with an eccentrically disposed cavity, a torsional helical spring in the bore includding ends seated in the cavities, a pin seated in the hole and, erforations, and a 'locking pin loose in the s ot and fixed in the plunger. 4. In a screw driver of the character described, a handle, a shaft comprising a secoint and provided with a central longitu inal bore bifurcating the point, a lateral bayonet slot, and with lateral 'perforations, and a section fixed at one end to the handle, and including a terminal re` dis osed eccentrically to the opening, anY

duced portion in thebore provided with a central longitudinal opening in its nd, a transverse hole, and with a cavity lin the end osclllatory gripping plunger comprising a body portion slidally mounted in the bore and provided at one end with an eceen'trically disposed cavity, and alreduced forward end portion terminating in a tip movable in the ifurcation of` the point' of the first section,

a stem upon the rear end ofthe plunger body slidable in said opening/f a torsional helical l spring in the bore surrounding the stem inuding ends in the cavities, a pin in the hole and perforations, and a locking pin in the blody portion of the plunger slidable in the s ot.

5. In a screw driver of the'character described, a handle, a shaft iixed in\the handle includin a broad point and provided with signature.

an axial ore bifurcating the oint, andwith a bayonet slot intermediate its lengthv comprising a lon 'tudinal and a'transverse pbrtion, a lon ltudinallyA yieldin oscillatory plunger sli ably-mounted in t e bore and normally projecting beyond the point, and coterminal with the point when in rearmost position, a locking pin in the plunger slidable 1n both'portions o the slot and means actuated by the retreat of the lunger for automatically impelling the loc ingpin into the transverse portion of the slot when the tip reaches a position coterminal with the point.

` vvIn testimony whereof I have aixed my EMiL MUELLER. 

